blog: Added idf.py extensions article

Author: Marek Fiala

assets/img/authors/marek-fiala.webp

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+---
+title: "Extending idf.py: Create custom commands for your ESP-IDF workflow"
+date: "2025-10-10"
+showAuthor: false
+authors:
+  - "marek-fiala"
+tags: ["ESP-IDF", "idf.py", "CLI", "Extensions", "Development Tools"]
+summary: "Learn how to extend idf.py with custom commands for your development workflow. This guide covers both component-based extensions for project-specific tools and Python package extensions for reusable commands, with practical examples and best practices for seamless integration."
+---
+
+<!-- TODO[Remove after ESP-IDF v6.0 release]
+Note: This article mentions ESP-IDF v6.0. Once it is released, remove the note below about development status.
+Context: Developer Portal's GitLab MR `88#note_2327272`
+ReviewDate: 2026-01-15
+Tags: ESP-IDF v6.0, obsolete
+-->
+
+What if you could extend `idf.py` with your own custom commands tailored to your specific workflow? With the ESP-IDF v6.0 and newer (to be released soon), you can do exactly that through a powerful extension system that lets you add project-specific tools or distribute reusable commands across your projects.
+
+Before we dive into extensions, let’s recall what `idf.py` gives you out of the box. It’s the central command-line tool for ESP-IDF that allows you to:
+
+- Set the target chip using `idf.py set-target` (like esp32)
+- Tweak your project settings using `idf.py menuconfig`
+- Build your application using `idf.py build`
+- Flash it using `idf.py -p PORT flash`
+- Watch the logs in real time using `idf.py monitor`
+
+For most developers, the daily cycle is simply **build → flash → monitor** — all streamlined under one command.
+
+## Why extend idf.py?
+
+Sometimes, though, the built-in commands aren’t enough. Maybe you need a custom deployment command that packages your firmware with metadata, or perhaps you want to integrate with your CI/CD pipeline through specialized build targets. Rather than maintaining separate scripts, you can now integrate these directly into `idf.py`, giving you:
+
+- **Unified interface**: All your tools accessible through the familiar `idf.py` command
+- **Consistent help system**: Your commands appear in `idf.py --help` with proper documentation
+- **Shared options**: Leverage existing global options like `--port` and `--build-dir`
+- **Dependency management**: Ensure commands run in the right order automatically
+
+## Two ways to extend idf.py
+
+ESP-IDF supports two extension mechanisms, each suited for different use cases:
+
+- Component-based extensions
+- Python package extensions
+
+### Component-based extensions
+
+This is the case for project-specific commands that should only be available when working with a particular project or component.
+
+**How it works**: Place a file named `idf_ext.py` in your component directory. ESP-IDF automatically discovers and loads extensions from this file **after the project is configured** with `idf.py reconfigure` or `idf.py build`. Within the component-based extension, the name of the file is important, as `idf.py` searches exactly for `idf_ext.py`. 
+
+**Note**: You may also place `idf_ext.py` in the project root instead of a component. This option has existed in earlier ESP-IDF versions and works the same way, but using a dedicated component is recommended for clarity and reusability.
+
+#### Step 1: Create the extension file
+
+- Create a new component (or use an existing one).
+- Inside the component, add a file named `idf_ext.py`.
+- This file must implement an `action_extensions` function returning a dictionary that describes your new commands, options, and callbacks.
+
+**Example (sensor manager)**:
+In this example, we’ll add a new command sensor-info that prints configuration details about sensors in your project. Start by creating a component called `sensor_manager`:
+
+```bash
+# Create the component using idf.py
+idf.py create-component -C components sensor_manager
+```
+
+Then, inside your component directory `components/sensor_manager/`, create `idf_ext.py` Python file and place the following code:
+
+```python
+from typing import Any
+import click
+
+def action_extensions(base_actions: dict, project_path: str) -> dict:
+    def sensor_info(subcommand_name: str, ctx: click.Context, global_args: dict, **action_args: Any) -> None:
+        sensor_type = action_args.get('type', 'all')
+        verbose = getattr(global_args, 'detail', False)
+        
+        print(f"Running {subcommand_name} for sensor type: {sensor_type}")
+        if verbose:
+            print(f"Project path: {project_path}")
+            print("Detailed sensor configuration would be displayed here...")
+
+    def global_callback_detail(ctx: click.Context, global_args: dict, tasks: list) -> None:
+        if getattr(global_args, 'detail', False):
+            print(f"About to execute {len(tasks)} task(s): {[t.name for t in tasks]}")
+
+    return {
+        "version": "1",
+        "global_options": [
+            {
+                "names": ["--detail", "-d"],
+                "is_flag": True,
+                "help": "Enable detailed output for all commands",
+            }
+        ],
+        "global_action_callbacks": [global_callback_detail],
+        "actions": {
+            "sensor-info": {
+                "callback": sensor_info,
+                "short_help": "Display sensor configuration",
+                "help": "Show detailed information about sensor configuration and status",
+                "options": [
+                    {
+                        "names": ["--type", "-t"],
+                        "help": "Sensor type to query (temperature, humidity, pressure, or all)",
+                        "default": "all",
+                        "type": click.Choice(['temperature', 'humidity', 'pressure', 'all']),
+                    }
+                ]
+            },
+        },
+    }
+```
+
+#### Step 2: Register the component
+
+- Ensure the new component is registered in your project’s CMakeLists.txt.
+- Further information on how to register commponents can be found in [Espressif documentation](https://docs.espressif.com/projects/esp-idf/en/stable/api-guides/build-system.html#component-requirements).
+
+<!-- Now you need to make sure your component is registered in your project's main `CMakeLists.txt`: -->
+
+**Example (sensor manager)**:
+Update your project's main `CMakeLists.txt`
+```cmake
+idf_component_register(
+    SRCS "main.c"
+    INCLUDE_DIRS "."
+    REQUIRES "sensor_manager"  # This makes the extension available
+)
+```
+
+#### Step 3: Load and test
+- Reconfigure or build the project to let ESP-IDF discover the extension.
+- Run idf.py help to check that your new command appears.
+- Test the new command with its options.
+
+**Example (sensor manager)**: In our case, the extension adds the `sensor-info` command:
+
+```bash
+# Configure the project to discover the extension
+idf.py reconfigure
+
+# Check that your command appears in help
+idf.py --help
+
+# Try your new command
+idf.py sensor-info --type temperature
+idf.py --detail sensor-info --type all
+```
+
+### Python package extensions
+
+This is ideal for reusable tools that you want to share across multiple projects or distribute to your team.
+
+**How it works**: Create a Python package with an entry point in the `idf_extension` group. Once installed, the extension is available globally for all projects.
+
+#### Step 1: Create the package structure
+
+- Create a new folder for your tool.
+- Add a `pyproject.toml` file to describe the package.
+- Inside the folder, create a subfolder with the same name, which will contain your Python code.
+- Inside that subfolder, add `__init__.py` and a Python file for the extension (e.g., `esp_ext.py`). 
+  - Unlike the fixed `idf_ext.py` in component-based extensions, the filename here is flexible because it is explicitly referenced in `pyproject.toml`. 
+  - For clarity and consistency, it’s recommended to prefix it with your tool name and suffix it with `_ext.py`. 
+
+The resulting structure should look like this:
+
+```bash
+my_sensor_tools/
+├── pyproject.toml  # describe the package here
+├── my_sensor_tools/ # place your Python code here
+│   ├── __init__.py
+│   └── esp_ext.py
+```
+
+#### Step 2: Fill the extension file
+
+- Implement the `action_extensions` function inside your package’s Python file.
+
+**Example (sensor manager)**:
+
+Here we simply copy the `action_extensions` function from the component example into `my_sensor_tools/esp_ext.py`.
+
+#### Step 3: Configure and install
+
+- Define the Python entry-point in your `pyproject.toml` under `[project.entry-points.idf_extension]`.
+  - Use the format name: `package.module:function`.
+- Install the package (for development, use `pip install -e .`).
+- The new command will now be globally available in any ESP-IDF project.
+
+<!-- On the final step, you will need to create the `pyproject.toml` file: -->
+**Example (sensor manager)**:
+
+The `pyproject.toml` file for our example could look like this:
+
+```toml
+[project]
+name = "my-sensor-tools"
+version = "1.0.0"
+
+# Register the extension under the `idf_extension` group,
+# so ESP-IDF can automatically discover it
+[project.entry-points.idf_extension]
+my_sensor_tools = "my_sensor_tools.esp_ext:action_extensions"
+```
+
+Install and use:
+
+```bash
+# Install in development mode
+cd my_sensor_tools
+pip install -e .
+
+# Your command is now available in any ESP-IDF project
+cd my_sensor_tools/
+idf.py sensor-info --type temperature
+idf.py --detail sensor-info --type all
+```
+
+## Naming conventions
+
+- **Avoid conflicts**: Your commands cannot override built-in `idf.py` commands like `build`, `flash`, or `monitor`
+- **Use descriptive names**: Prefer `sensor-info` over `info` to avoid ambiguity
+- **Package prefixes**: For Python package extensions, consider prefixing commands with your tool name
+
+## Advanced features
+
+Do you need something extra? Beyond simple commands, the extension system also gives you ways to define global options, control execution order, and build richer command-line interfaces. These features let you create tools that feel fully integrated with the rest of `idf.py`.
+
+### Global options and callbacks
+
+The extension system supports sophisticated features for power users:
+
+**Global options**: Define options that work across all commands. Can be exposed under `global_args` parameter.
+
+**Global callbacks**: Functions that run before any tasks execute, perfect for validation, logging, or injecting additional tasks based on global options.
+
+### Dependencies and order management
+
+Ensure your commands run in the correct sequence:
+
+```python
+"actions": {
+    "deploy": {
+        "callback": deploy_firmware,
+        "dependencies": ["all"],  # Always build before deploying
+        "order_dependencies": ["flash"],  # If flash is requested, run it before deploy
+        "help": "Deploy firmware to production servers"
+    }
+}
+```
+
+### Rich argument support
+
+Support complex command-line interfaces:
+
+```python
+"options": [
+    {
+        "names": ["--config-file", "-c"],
+        "type": click.Path(exists=True),
+        "help": "Configuration file path"
+    },
+    {
+        "names": ["--verbose", "-v"],
+        "count": True,  # -v, -vv, -vvv for different verbosity levels
+        "help": "Increase verbosity (use multiple times)"
+    }
+],
+"arguments": [
+    {
+        "names": ["targets"],
+        "nargs": -1,  # Accept multiple targets
+        "required": True
+    }
+]
+```
+
+For more details on the extension API and additional features, see the [Click documentation](https://click.palletsprojects.com/) for argument types and the [ESP-IDF documentation](https://docs.espressif.com/projects/esp-idf/en/latest/api-guides/tools/idf-py.html#extending-idf-py) for the complete extension reference.
+
+## Conclusion
+
+The `idf.py` extension system opens up powerful possibilities for customizing your ESP-IDF development workflow. Whether you're adding simple project-specific helpers or building sophisticated development tools, extensions let you integrate seamlessly with the existing ESP-IDF ecosystem.
+
+Start small with a component-based extension for your current project, then graduate to distributable packages as your tools mature.
+
+## What's next?
+
+- Explore the [full extension API documentation](https://docs.espressif.com/projects/esp-idf/en/latest/api-guides/tools/idf-py.html#extending-idf-py) for advanced features
+- Check out existing extensions in the ESP-IDF codebase for inspiration
+
+Happy extending!

content/blog/2025/10/idf_py_extension/featured.webp

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 {
     "name": "Marek Fiala",
-    "bio": "",
-    "image": ""
+    "bio": "SW Developer at Espressif",
+    "image": "img/authors/marek-fiala.webp"
 }